Chemical mechanical polishing or planarization (CMP) is a technique of polishing materials including semiconductor substrates and films overlying such substrates, which provides a high degree of uniformity and planarity. The process is used to remove high elevation features on films created during the fabrication of a microelectronic circuitry on the substrate, or to remove a layer of film to reveal the circuitry buried underneath the film. In some cases, the process can planarize semiconductor slices prior to the fabrication of microelectronic circuitry thereon.
Some conventional chemical mechanical polishing processes uses an apparatus having a single large polishing pad positioned on a platen, against which a substrate is positioned for polishing. A positioning member positions and biases the substrate to be polished against the polishing pad, which is rotating. A chemical slurry, which is likely to have abrasive materials, is typically maintained on the polishing pad to modify the polishing characteristics of the polishing pad and to enhance the polishing of the substrate or films.
Corresponding reference characters indicate corresponding components throughout the several views of the drawings. Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of various embodiments of the present invention. Also, common but well-understood elements that are useful or necessary in a commercially feasible embodiment are often not depicted in order to facilitate a less obstructed view of these various embodiments of the present invention.